Comparison Of Tilt When Using Visual Direction Or Anatomical Landmarks As A Reference Line

Understanding tilt and decentration of intraocular lenses (IOLs) is crucial for assessing modern IOLs. However, both parameters are relative to a reference point/angle, which varies based on techniques and analysis methods. We investigated the agreement in assessing tilt and decentration between anatomical landmarks and visual direction.

The study was conducted at the hospital eye clinic, Plymouth Hospital University NHS Trust, United Kingdom, and the University Eye and Vision Research Unit, University of Plymouth, United Kingdom.

Tilt and decentration assessment was performed on 49 subjects who underwent phacoemulsification and Tecnis monofocal IOL implantation 3-12 months prior to the study visit. Subjects were evaluated using Scheimpflug (Pentacam) image analysis and anterior eye optical coherence tomography (Tomy Casia AS-OCT). Image analysis was conducted on the R platform, fitting a second-order polynomial to the anterior and posterior lens surfaces to determine the IOL equator. Data were analyzed using Bland-Altman plots, Pearson’s correlation coefficient, and repeated measures analysis of variance.

There was a significant difference in tilt (p < 0.01) with both OCT and Scheimpflug when using anatomical landmarks and visual direction as a reference, with visual direction providing greater tilt values. Bland and Altman analysis demonstrated that tilt results using different reference points were not comparable. Decentration showed more similarity when using pupil margins as anatomical reference points.

Assessment of tilt varies and depends on the reference line when assessed with OCT and Pentacam. Results using anatomical landmarks are not comparable with visual direction.